Photographic flashlamp unit

ABSTRACT

A flashcube with self-contained members for firing percussivetype lamps disposed therein. Each lamp in the flashcube has its own firing mechanism associated therein in the form of a wire torsional spring.

United States Patent Shaffer et al.

[451 Sept. 19, 1972 1 PHOTOGRAPHIC FLASHLAMP UNIT [72] Inventors: John W. Shaffer; Sedgwick R.

Bennett, both of Williamsport, Pa.

[73] Assignee: Sylvania Electric Products Inc.

[22] Filed: Nov. 4, 1968 [21] Appl. No.: 773,178

[52] US. Cl ..240/l.3, 431/93 [51] Int. Cl. ..G03b 15/02 [58] Field of Search.....95/ll L; 240/13; 431/93, 94,

[56] References Cited UNITED STATES PATENTS Kobayashi ..431/93 X 3,319,058 5/ 1967 Toomey et a1 ..240/ 1.3 3,508,478 4/1970 Brooks ..240/1.3 X 3,537,367 11/1970 Van Duser ..95/11 FOREIGN PATENTS 0R APPLICATIONS 635,443 9/1936 Germany ..431/93 813,360 5/1959 Great Britain ..95/11 Primary Examiner-John M. Horan Assistant Examiner-Fred L. Braun Attorney-Norman J. OMalley and Joseph C. Ryan [5 7] ABSTRACT A flashcube with se1f-contained members for firing percussive-type lamps disposed therein. Each lamp in the flashcube has its own firing mechanism associated therein in the form of a wire torsional spring.

4 Claims, 2 Drawing figures PATENEFEDSEP 19 I972 JOHN W. SHAFFER SEDGWICK R. BENNETT INVENTOR W ATTORNEY PHOTOGRAPI-IIC FLASI-ILAMP UNIT This invention relates to the manufacture of multilamp photographic flashlamp units and more particularly to the means employed to fire the lamps.

The introduction of the multilamp photographic flashlamp unit, generally known as a flashcube, represented a significant advance in the art. It eliminated the need for flashguns and it eliminated the need for built-in reflectors. It also eliminated handling of the flashlamp individually. However, it did not eliminate the need for batteries.

One of the most chronic problems and perhaps most exasperating circumstance with which the average amateur photographer is confronted is weak batteries-batteries too weak to fire the lamp properly or in synchronization. The average amateur photographer will usually have a spare flashlamp or two but rarely if ever will he have a pair of spare fresh batteries. Thus a single shot, or more probably a whole sequence of shots will be lost. Dry cell batteries, by their very nature tend to lose their strength gradually over an extended period of time. Many amateur photographers take flash pictures less than half a dozen times a year, thus providing more than enough time between uses for the batteries to deteriorate from strong to weak-from operativeness to inoperativeness.

More recently a percussive-type flashlamp has been suggested, i.e., a flashlamp which does not depend on a source of electrical energy for its operation. Generally speaking, a percussive-type photoflash lamp comprises an hermetically sealed, light-transmitting envelope containing a source of actinic light and having a primer secured thereto. More particularly, the percussive-type photoflash lamp may comprise a length of glass tubing constricted to a tip at one end thereof and having a primer sealed therein at the other end thereof. The length of glass tubing which defines the lamp envelope contains a combustible such as shredded zirconium foil and a combustion-supporting gas such as oxygen. The primer may comprise a metal tube or cup with a charge of fulminating material and an anvil supported therein. Operation of the lamp is initiated by an impact onto the metal tube or cup sufficient to cause deflagration of the fulminating material and thus ignition of the'combustible in the lamp envelope. I-leretofore, several means have been suggested for firing these percussive-type flashlamps, all of which involve some form of spring mechanism built into the camera with the spring serving as an almost frictionless moving hammer. Cocking of the spring is usually accomplished by the film transport and/or cocking of the lens shutter mechanism, whether or not there is a flashlamp assembly being used for the picture taking. Cameras in the lower price ranges are built to withstand about 2,000 operations. Thus the firing spring must be able to withstand the stresses necessary to deliver the required energy and impact velocity for about 2,000 pictures. Only springs which are never overstressed in use and therefore have to be overdimensioned are suitable for such a task. However, the available space inside small cameras and the force required to cock the spring make it exceedingly difficult, and in some cases practically impossible, to provide a spring having the diameter, length and deflection characteristics necessary to develop the required energy at the required velocity. Thus in many cases such firing mechanisms frequently have to be underdimensioned and as a result may not operate satisfactorily for the full life of the camera.

In view of the foregoing, the principal object of this invention is to provide a simple, effective and efficient means for firing percussive-type flashlamps.

This and other objects, advantages and features are attained, in accordance with the principles of this invention, by providing a flashcube with self-contained means for firing the percussive-type lamps disposed therein. In accordance with the principles of this invention, each lamp in the flashcube has associated therewith within the flashcube its own firing mechanism in the form of a wire torsional spring. More particularly, four wire torsional springs pass through the flashcube on the diagonals thereof and between the reflectors with the lower end of each spring bent to a angle to form a striker.

In the specific embodiment of the invention illustrated in the accompanying drawing:

FIG. 1 is a perspective view of a flashcube embodying the principles of this invention with a portion of the flashcube broken away for clarity of illustration.

FIG. 2 is a bottom view of the flashcube of FIG. 1.

In the specific embodiment illustrated in the accompany drawing, the flashcube 2 comprises a substantially rectangular base 4 along each side of which a percussive-type flashlamp 6 is arranged. Each lamp 6 is provided with its own reflector 8 and the assemblage of lamps and reflectors is enclosed in a transparent container 10 secured to the base 4. Each lamp 6 comprises an hermetically sealed light-transmitting envelope 12 having a primer depending therefrom and a filling of combustible foil 14 and a combustion-supporting gas disposed therein. The primer comprises a metal tube 16 within which an anvil and a charge of fulminating material are disposed. The base 4 (FIGS. 1 and 2) is provided with a center post 18 having a central aperture 20 and four wings 22 extending radially therefrom. The outer end of each wing 22 is provided with a pocket 24 within which a primer tube 16 is seated.

In the specific embodiment of the invention illustrated in FIGS. 1 and 2, four wire torsional springs 1 pass vertically through the flashcube on the diagonals thereof and between the reflectors 8. The upper end segment of each spring 1 passes through a hole 9 in the top of the container 10, is bent a 90angle and anchored in a hole 11. The lower end segment of each spring is bent at 90angle to form a striker 3. Each wire torsional spring 1 is oriented so that its striker 3 is in contact with the primer tube 16 of a lamp 6 when in a nonstressed condition as shown in phantom in FIG. 2. These springs 1 may be prestressed by rotating the strikers 3 thereof counterclockwise as viewed in FIG. 2 until they reach an interlocking engagement with catches 5 located at each corner of the base 4. The catches 5 may be molded as an integral part of the base 4, being attached thereto at 7 and free to flex at 9. Alternatively, the catches 5 may be rigid and release of the springs 1 may be effected by flexure of the strikers 3 thereof. Since the center post 18 is provided with a central aperture 20 as a means for seating the flashcube on a socket or receiving member of a camera, the means for flexing the catch 5 associated with a lamp in firing position, to release the striker 3 and thus permit it to swing clockwise as viewed in FIG. 2 to strike the primer tube 16 and thus fire the lamp, may comprise a pin, finger or the like forming a part of the camera and connected to the shutter release mechanism thereof to insure synchronization of the firing of the lamp with the tripping of the shutter.

Various spring energies and velocities are readily attained by the use of different spring diameters and striker lengths. By way of example, extremely good flash reliability has been obtained with 0.031 inch diameter music wire having a torsional section 1.3 inch long and a striker 0.3 inch long. The measured energy stored by twisting the striker 30from its rest position was 1.8 inch-ounces and the impact velocity was calculated to be about 2,000 inches per second.

It will be readily apparent to those skilled in the art that the flashcube of this invention is characterized by a number of significant advantages. For example, the torsional spring arrangement provides high velocity impact without attendant high stressing and thus makes possible the marketing of such units in a cocked or preloaded condition so that for operation all the camera must do is to release the striker. The use of preloaded springs is of particular advantage with respect to flashcubes having percussive-type flashlamps used in conjunction with miniature and subminiature cameras which maynot have sufficient internal working space to accommodate a flash device of the necessary size and may not be able to supply the required cocking force. The impact energy and velocity are controlled by the flashcube manufacturer and thus lamp flesh reliability is not dependent upon a camera mechanism providing sufficient impact. The moving mass of such torsional spring powered flashcubes is the lowest available in any percussive flash device for a given energy, thus minimizing camera movement and vibration which could blur pictures, particularly with subminiature cameras.

Despite the foregoing advantages, the flashcube could, of course, also be marketed uncocked if desired, in which case the camera would supply the means to deflect the strikers as well as the means to release them. In such cases, it may be desirable to omit the catches 5.

What we claim is:

1. A photographic flashlamp unit for use with a camera having a socket for receiving said unit, said unit comprising:

a platform;

a plurality of flashlamps mounted on said platform, each of said flashlamps comprising an hermetically sealed, light-transmitting envelope having a source of actinic light disposed therein and a primer depending therefrom each of said primers including a charge of fulminating material;

and a substantially linear torsional spring device associated with each of said primers and mounted on said platform for striking said primers to cause deflagration of said fulminating material and ignition of said source of actinic light.

2. The combination of claim 1 in which said torsional spring device is normally cocked.

3. The combination of claim 1 and a plurality of reflectors located on said platform, one for each of said flashlamps, said reflectors being arranged so that the rear faces thereof define a central chamber; and said torsional spring devices being located primarily within sai c tral ch ber.

2. 'fiie com iiiation of claim 3 and a container enclosing said lamps and reflectors, the major central segment of said torsional spring devices being located within said central chamber, the lower end thereof being bent at about a angle to define a striker and the upper end thereof being anchored in the top of said container. 

1. A photographic flashlamp unit for use with a camera having a socket for receiving said unit, said unit comprising: a platform; a plurality of flashlamps mounted on said platform, each of said flashlamps comprising an hermetically sealed, lighttransmitting envelope having a source of actinic light disposed therein and a primer depending therefrom each of said primers including a charge of fulminating material; and a substantially linear torsional spring device associated with each of said primers and mounted on said platform for striking said primers to cause deflagration of said fulminating material and ignition of said source of actinic light.
 2. The combination of claim 1 in which said torsional spring device is normally cocked.
 3. The combination of claim 1 and a plurality of reflectors located on said platform, one for each of said flashlamps, said reflectors being arranged so that the rear faces thereof define a central chamber; and said torsional spring devices being located primarily within said central chamber.
 4. The combination of claim 3 and a container enclosing said lamps and reflectors, the major central segment of said torsional spring devices being located within said central chamber, the lower end thereof being bent at about a 90* angle to define a striker and the upper end thereof being anchored in the top of said container. 